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Linus Torvalds 26ff969926 Rust changes for v7.1
Toolchain and infrastructure:
 
  - Bump the minimum Rust version to 1.85.0 (and 'bindgen' to 0.71.1).
 
    As proposed in LPC 2025 and the Maintainers Summit [1], we are going
    to follow Debian Stable's Rust versions as our minimum versions.
 
    Debian Trixie was released on 2025-08-09 with a Rust 1.85.0 and
    'bindgen' 0.71.1 toolchain, which is a fair amount of time for e.g.
    kernel developers to upgrade.
 
    Other major distributions support a Rust version that is high enough
    as well, including:
 
      + Arch Linux.
      + Fedora Linux.
      + Gentoo Linux.
      + Nix.
      + openSUSE Slowroll and openSUSE Tumbleweed.
      + Ubuntu 25.10 and 26.04 LTS. In addition, 24.04 LTS using
        their versioned packages.
 
    The merged patch series comes with the associated cleanups and
    simplifications treewide that can be performed thanks to both bumps,
    as well as documentation updates.
 
    In addition, start using 'bindgen''s '--with-attribute-custom-enum'
    feature to set the 'cfi_encoding' attribute for the 'lru_status' enum
    used in Binder.
 
    Link: https://lwn.net/Articles/1050174/ [1]
 
  - Add experimental Kconfig option ('CONFIG_RUST_INLINE_HELPERS') that
    inlines C helpers into Rust.
 
    Essentially, it performs a step similar to LTO, but just for the
    helpers, i.e. very local and fast.
 
    It relies on 'llvm-link' and its '--internalize' flag, and requires
    a compatible LLVM between Clang and 'rustc' (i.e. same major version,
    'CONFIG_RUSTC_CLANG_LLVM_COMPATIBLE'). It is only enabled for two
    architectures for now.
 
    The result is a measurable speedup in different workloads that
    different users have tested. For instance, for the null block driver,
    it amounts to a 2%.
 
  - Support global per-version flags.
 
    While we already have per-version flags in many places, we didn't
    have a place to set global ones that depend on the compiler version,
    i.e. in 'rust_common_flags', which sometimes is needed to e.g. tweak
    the lints set per version.
 
    Use that to allow the 'clippy::precedence' lint for Rust < 1.86.0,
    since it had a change in behavior.
 
  - Support overriding the crate name and apply it to Rust Binder, which
    wanted the module to be called 'rust_binder'.
 
  - Add the remaining '__rust_helper' annotations (started in the
    previous cycle).
 
 'kernel' crate:
 
  - Introduce the 'const_assert!' macro: a more powerful version of
    'static_assert!' that can refer to generics inside functions or
    implementation bodies, e.g.:
 
        fn f<const N: usize>() {
            const_assert!(N > 1);
        }
 
        fn g<T>() {
            const_assert!(size_of::<T>() > 0, "T cannot be ZST");
        }
 
    In addition, reorganize our set of build-time assertion macros
    ('{build,const,static_assert}!') to live in the 'build_assert'
    module.
 
    Finally, improve the docs as well to clarify how these are different
    from one another and how to pick the right one to use, and their
    equivalence (if any) to the existing C ones for extra clarity.
 
  - 'sizes' module: add 'SizeConstants' trait.
 
    This gives us typed 'SZ_*' constants (avoiding casts) for use in
    device address spaces where the address width depends on the hardware
    (e.g. 32-bit MMIO windows, 64-bit GPU framebuffers, etc.), e.g.:
 
        let gpu_heap = 14 * u64::SZ_1M;
        let mmio_window = u32::SZ_16M;
 
  - 'clk' module: implement 'Send' and 'Sync' for 'Clk' and thus simplify
    the users in Tyr and PWM.
 
  - 'ptr' module: add 'const_align_up'.
 
  - 'str' module: improve the documentation of the 'c_str!' macro to
    explain that one should only use it for non-literal cases (for the
    other case we instead use C string literals, e.g. 'c"abc"').
 
  - Disallow the use of 'CStr::{as_ptr,from_ptr}' and clean one such use
    in the 'task' module.
 
  - 'sync' module: finish the move of 'ARef' and 'AlwaysRefCounted'
    outside of the 'types' module, i.e. update the last remaining
    instances and finally remove the re-exports.
 
  - 'error' module: clarify that 'from_err_ptr' can return 'Ok(NULL)',
    including runtime-tested examples.
 
    The intention is to hopefully prevent UB that assumes the result of
    the function is not 'NULL' if successful. This originated from a case
    of UB I noticed in 'regulator' that created a 'NonNull' on it.
 
 Timekeeping:
 
  - Expand the example section in the 'HrTimer' documentation.
 
  - Mark the 'ClockSource' trait as unsafe to ensure valid values for
    'ktime_get()'.
 
  - Add 'Delta::from_nanos()'.
 
 'pin-init' crate:
 
  - Replace the 'Zeroable' impls for 'Option<NonZero*>' with impls of
    'ZeroableOption' for 'NonZero*'.
 
  - Improve feature gate handling for unstable features.
 
  - Declutter the documentation of implementations of 'Zeroable' for
    tuples.
 
  - Replace uses of 'addr_of[_mut]!' with '&raw [mut]'.
 
 rust-analyzer:
 
  - Add type annotations to 'generate_rust_analyzer.py'.
 
  - Add support for scripts written in Rust ('generate_rust_target.rs',
    'rustdoc_test_builder.rs', 'rustdoc_test_gen.rs').
 
  - Refactor 'generate_rust_analyzer.py' to explicitly identify host and
    target crates, improve readability, and reduce duplication.
 
 And some other fixes, cleanups and improvements.
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Merge tag 'rust-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

Pull Rust updates from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Bump the minimum Rust version to 1.85.0 (and 'bindgen' to 0.71.1).

     As proposed in LPC 2025 and the Maintainers Summit [1], we are
     going to follow Debian Stable's Rust versions as our minimum
     versions.

     Debian Trixie was released on 2025-08-09 with a Rust 1.85.0 and
     'bindgen' 0.71.1 toolchain, which is a fair amount of time for e.g.
     kernel developers to upgrade.

     Other major distributions support a Rust version that is high
     enough as well, including:

       + Arch Linux.
       + Fedora Linux.
       + Gentoo Linux.
       + Nix.
       + openSUSE Slowroll and openSUSE Tumbleweed.
       + Ubuntu 25.10 and 26.04 LTS. In addition, 24.04 LTS using
         their versioned packages.

     The merged patch series comes with the associated cleanups and
     simplifications treewide that can be performed thanks to both
     bumps, as well as documentation updates.

     In addition, start using 'bindgen''s '--with-attribute-custom-enum'
     feature to set the 'cfi_encoding' attribute for the 'lru_status'
     enum used in Binder.

     Link: https://lwn.net/Articles/1050174/ [1]

   - Add experimental Kconfig option ('CONFIG_RUST_INLINE_HELPERS') that
     inlines C helpers into Rust.

     Essentially, it performs a step similar to LTO, but just for the
     helpers, i.e. very local and fast.

     It relies on 'llvm-link' and its '--internalize' flag, and requires
     a compatible LLVM between Clang and 'rustc' (i.e. same major
     version, 'CONFIG_RUSTC_CLANG_LLVM_COMPATIBLE'). It is only enabled
     for two architectures for now.

     The result is a measurable speedup in different workloads that
     different users have tested. For instance, for the null block
     driver, it amounts to a 2%.

   - Support global per-version flags.

     While we already have per-version flags in many places, we didn't
     have a place to set global ones that depend on the compiler
     version, i.e. in 'rust_common_flags', which sometimes is needed to
     e.g. tweak the lints set per version.

     Use that to allow the 'clippy::precedence' lint for Rust < 1.86.0,
     since it had a change in behavior.

   - Support overriding the crate name and apply it to Rust Binder,
     which wanted the module to be called 'rust_binder'.

   - Add the remaining '__rust_helper' annotations (started in the
     previous cycle).

  'kernel' crate:

   - Introduce the 'const_assert!' macro: a more powerful version of
     'static_assert!' that can refer to generics inside functions or
     implementation bodies, e.g.:

         fn f<const N: usize>() {
             const_assert!(N > 1);
         }

         fn g<T>() {
             const_assert!(size_of::<T>() > 0, "T cannot be ZST");
         }

     In addition, reorganize our set of build-time assertion macros
     ('{build,const,static_assert}!') to live in the 'build_assert'
     module.

     Finally, improve the docs as well to clarify how these are
     different from one another and how to pick the right one to use,
     and their equivalence (if any) to the existing C ones for extra
     clarity.

   - 'sizes' module: add 'SizeConstants' trait.

     This gives us typed 'SZ_*' constants (avoiding casts) for use in
     device address spaces where the address width depends on the
     hardware (e.g. 32-bit MMIO windows, 64-bit GPU framebuffers, etc.),
     e.g.:

         let gpu_heap = 14 * u64::SZ_1M;
         let mmio_window = u32::SZ_16M;

   - 'clk' module: implement 'Send' and 'Sync' for 'Clk' and thus
     simplify the users in Tyr and PWM.

   - 'ptr' module: add 'const_align_up'.

   - 'str' module: improve the documentation of the 'c_str!' macro to
     explain that one should only use it for non-literal cases (for the
     other case we instead use C string literals, e.g. 'c"abc"').

   - Disallow the use of 'CStr::{as_ptr,from_ptr}' and clean one such
     use in the 'task' module.

   - 'sync' module: finish the move of 'ARef' and 'AlwaysRefCounted'
     outside of the 'types' module, i.e. update the last remaining
     instances and finally remove the re-exports.

   - 'error' module: clarify that 'from_err_ptr' can return 'Ok(NULL)',
     including runtime-tested examples.

     The intention is to hopefully prevent UB that assumes the result of
     the function is not 'NULL' if successful. This originated from a
     case of UB I noticed in 'regulator' that created a 'NonNull' on it.

  Timekeeping:

   - Expand the example section in the 'HrTimer' documentation.

   - Mark the 'ClockSource' trait as unsafe to ensure valid values for
     'ktime_get()'.

   - Add 'Delta::from_nanos()'.

  'pin-init' crate:

   - Replace the 'Zeroable' impls for 'Option<NonZero*>' with impls of
     'ZeroableOption' for 'NonZero*'.

   - Improve feature gate handling for unstable features.

   - Declutter the documentation of implementations of 'Zeroable' for
     tuples.

   - Replace uses of 'addr_of[_mut]!' with '&raw [mut]'.

  rust-analyzer:

   - Add type annotations to 'generate_rust_analyzer.py'.

   - Add support for scripts written in Rust ('generate_rust_target.rs',
     'rustdoc_test_builder.rs', 'rustdoc_test_gen.rs').

   - Refactor 'generate_rust_analyzer.py' to explicitly identify host
     and target crates, improve readability, and reduce duplication.

  And some other fixes, cleanups and improvements"

* tag 'rust-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (79 commits)
  rust: sizes: add SizeConstants trait for device address space constants
  rust: kernel: update `file_with_nul` comment
  rust: kbuild: allow `clippy::precedence` for Rust < 1.86.0
  rust: kbuild: support global per-version flags
  rust: declare cfi_encoding for lru_status
  docs: rust: general-information: use real example
  docs: rust: general-information: simplify Kconfig example
  docs: rust: quick-start: remove GDB/Binutils mention
  docs: rust: quick-start: remove Nix "unstable channel" note
  docs: rust: quick-start: remove Gentoo "testing" note
  docs: rust: quick-start: add Ubuntu 26.04 LTS and remove subsection title
  docs: rust: quick-start: update minimum Ubuntu version
  docs: rust: quick-start: update Ubuntu versioned packages
  docs: rust: quick-start: openSUSE provides `rust-src` package nowadays
  rust: kbuild: remove "dummy parameter" workaround for `bindgen` < 0.71.1
  rust: kbuild: update `bindgen --rust-target` version and replace comment
  rust: rust_is_available: remove warning for `bindgen` < 0.69.5 && libclang >= 19.1
  rust: rust_is_available: remove warning for `bindgen` 0.66.[01]
  rust: bump `bindgen` minimum supported version to 0.71.1 (Debian Trixie)
  rust: block: update `const_refs_to_static` MSRV TODO comment
  ...
2026-04-13 09:54:20 -07:00
arch Rust changes for v7.1 2026-04-13 09:54:20 -07:00
block block-7.0-20260305 2026-03-06 08:36:18 -08:00
certs Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
crypto This push contains the following changes: 2026-04-12 08:11:02 -07:00
Documentation Rust changes for v7.1 2026-04-13 09:54:20 -07:00
drivers Rust changes for v7.1 2026-04-13 09:54:20 -07:00
fs vfs-7.0-rc8.fixes 2026-04-10 08:40:49 -07:00
include RCU changes for v7.1 2026-04-13 09:36:45 -07:00
init Rust changes for v7.1 2026-04-13 09:54:20 -07:00
io_uring io_uring-7.0-20260403 2026-04-03 11:58:04 -07:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel RCU changes for v7.1 2026-04-13 09:36:45 -07:00
lib Rust changes for v7.1 2026-04-13 09:54:20 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm 8 hotfixes. All are cc:stable and 7 are for MM. 2026-04-07 10:24:44 -07:00
net vfs-7.0-rc8.fixes 2026-04-10 08:40:49 -07:00
rust Rust changes for v7.1 2026-04-13 09:54:20 -07:00
samples Landlock fix for v7.0-rc6 2026-03-26 12:03:37 -07:00
scripts Rust changes for v7.1 2026-04-13 09:54:20 -07:00
security proc: make PROC_MEM_FORCE_PTRACE the Kconfig default 2026-04-13 09:12:37 -07:00
sound ASoC: Fixes for v7.0 2026-04-09 07:00:53 +02:00
tools RCU changes for v7.1 2026-04-13 09:36:45 -07:00
usr kbuild: uapi: drop dependency on CC_CAN_LINK 2026-01-16 15:02:11 -07:00
virt KVM generic changes for 7.0 2026-03-11 18:01:55 +01:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-04-02 16:48:25 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rust: provide an option to inline C helpers into Rust 2026-03-30 02:03:52 +02:00
.mailmap MAINTAINERS, mailmap: Change Ulf Hansson's email 2026-04-07 14:17:48 +02:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml
COPYING
CREDITS MAINTAINERS: remove Thomas Falcon from IBM ibmvnic 2026-03-05 07:35:45 -08:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Rust changes for v7.1 2026-04-13 09:54:20 -07:00
Makefile Rust changes for v7.1 2026-04-13 09:54:20 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros
* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst